In certain types of medical emergencies a patient's heart stops working, which stops the blood from flowing. Without the blood flowing, organs like the brain will start becoming damaged, and the patient will soon die. Cardiopulmonary resuscitation (CPR) can forestall these risks. CPR includes performing repeated chest compressions to the chest of the patient, so as to cause the patient's blood to circulate some. CPR also includes delivering rescue breaths to the patient, so as to create air circulation in the lungs. CPR is intended to merely forestall organ damage and death, until a more definitive treatment is made available. Defibrillation is such a definitive treatment: it is an electric shock delivered deliberately to the patient's heart, in the hope of restoring their heart rhythm.
Guidelines by medical experts such as the American Heart Association provide parameters for CPR to cause the blood to circulate effectively. The parameters are for aspects such as the frequency of the compressions, the depth that they should reach, and the full release that is to follow each of them. The depth is sometimes required to reach 5 cm (2 in.). The parameters for CPR also include instructions for the rescue breaths.
Traditionally, CPR has been performed manually. A number of people have been trained in CPR, including some who are not in the medical professions, just in case they are bystanders in an emergency event.
Manual CPR may be ineffective, however. Indeed, the rescuer might not be able to recall their training, especially under the stress of the moment. And even the best trained rescuer can become fatigued from performing the chest compressions for a long time, at which point their performance may become degraded. In the end, chest compressions that are not frequent enough, not deep enough, or not followed by a full release may fail to maintain the blood circulation required to forestall organ damage and death.
The risk of ineffective chest compressions has been addressed with CPR chest compression machines. Such machines have been known by a number of names, for example CPR chest compression machines, CPR machines, mechanical CPR devices, cardiac compressors, CPR systems, and so on.
CPR chest compression machines typically hold the patient supine, which means lying on his or her back. Such machines then repeatedly compress and release the chest of the patient. In fact, they can be programmed to automatically follow the guidelines, by compressing and releasing at the recommended rate or frequency, while reaching a specific depth.